The invention relates to an apparatus for the compensation of crosswind forces and of other forces causing a lateral deviation of a motor vehicle from its track. The apparatus automatically influences the steering of the vehicle, independently of the actuation of the steering mechanism by the operator. Especially at high vehicle velocities, the straight running of motor vehicles is influenced by crosswind. Especially in vehicles in which the point of attack of the resultant wind force and the center of mass of the vehicle are separated by some distance in the longitudinal direction of the vehicle, the effects of crosswind create a turning moment about the vertical axis and this turning moment tends to cause a pivoting of the longitudinal vehicle axis from the nominal direction of motion if the center of mass is located at the rear. As a result, at high vehicle velocities, the vehicle deviates excessively from the nominal track in a short time and this effect is in addition to the lateral deviation due to the wind. The vehicle operator is therefore obliged to apply a counter-steering effort to keep the vehicle running straight.
When the crosswinds acting on the vehicle fluctuate rapidly in strength and/or direction, extraordinary demands are made on the driver's powers of attention and traffic safety is impaired because of premature driver fatigue.
Known installations of the types described above have the aim, therefore, of changing the oblique running angle of the steering wheels in the sense of counter-steering for equalization of wind drift when a crosswind influence is present.
Thus, in a device which has become known for the elimination of crosswind sensitivity in motor vehicles, at least one pressure sensor is provided at two opposite sides of the vehicle to sense the air pressure created by the crosswind and it includes a servo setting member, controlled by the differential pressure on the two sides of the vehicle, which displaces the front axle carrier with respect to the longitudinal vehicle members and, in this way, causes the wheels to turn in the sense of a counter-steering effort. This known installation has the disadvantage that pressure-actuated operating cylinders of large dimensions are required for changing the relative positions of the structural members. This leads to high construction costs and space requirements and furthermore, the wheel deflection does not always occur smoothly so that the driver is subject to irritation.
In another known installation, a servomotor is coupled to the steering gear during the occurrence of a crosswind and superimposes a crosswind-dependent compensation torque onto the steering torque provided by the driver. This known installation requires only a small space and engages smoothly and without jerking if properly designed. Furthermore, all known installations for the compensation of crosswind influences are such that their action is essentially proportional to the drift forces due to the crosswind. The compensating torque, which is superimposed on the driver's efforts, is uniformly applied by the equalization system, even during extended crosswind influence, and the driver is relieved of the necessity to apply a counter-steering effort. However, it is desirable that the driver be informed about longer lasting external influences acting on his vehicle so that he can adjust his long-term manner of driving.
It is possible, in principle, to design the previously known compensation installations in such a way that they compensate for the crosswind influences only partially and not to their full extent.
In that case, it is left to the driver to compensate for a portion of the drift by appropriate counter-steering movements and he retains a feeling for the crosswind forces acting on the vehicle because of the remaining required steering wheel torque. On the other hand, while the driver need no longer make large steering motions in order to maintain straight running, a portion of his attention is still taken up by the necessity for immediate reaction to a sudden onset of wind drift.